Self-patterning of a polydimethylsiloxane microlens array on functionalized substrates and characterization by digital holography

Microlens arrays are realized through a self-arrangement process of thin liquid polymeric polydimethylsiloxane (PDMS) film on a functionalized polar dielectric crystal substrate. The self-arrangement process is named the pyro-electro-wetting mechanism. The substrate, a LiNbO 3 (LN) z-cut wafer, has been micro-engineered with periodically poled ferroelectric domains, with the aim to provide an appropriate wettability patterning induced by a thermal stimulus. Different experimental procedures have been explored demonstrating that arrays of thousands of microlenses, having a diameter size of 100 µm and focal lengths ranging between 300 and 1100 µm, can be fabricated. Furthermore, a microscope interference method based on digital holography is adopted for microlens characterization.